Efficient sky-blue organic light-emitting diodes using a highly horizontally oriented thermally activated delayed fluorescence emitter

Funding: Deutsche Forschungsgemeinschaft (Grant Number(s): SFB1176), Engineering and Physical Sciences Research Council (Grant Number(s): EP/P010482/1), China Scholarship Council (Grant Number(s): 201606890009), H2020 Marie Skłodowska-Curie Actions (Grant Number(s): 812872).Organic thermally activated delayed fluorescent (TADF) materials can harvest 100% of the electrically generated excitons as a result of their small singlet-triplet energy difference. However, maximizing the External Quantum Efficiency (EQE) of a device also requires enhancing the light-outcoupling efficiency. In this work, we present a new Acceptor-Donor-Acceptor (ADA) emitter employing an indolocarbazole donor and diphenyltriazine acceptors that shows nearly-completely horizontal orientation regardless of the host matrix, leading to a sky-blue OLED (λEL=483nm, CIE coordinates of 0.17, 0.32) with EQEMAX of 22.1%, a maximum luminance of 7800 cd/m2 and blue emission.Publisher PDFPeer reviewe